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Not him, but caffeine essentially just tricks your brain into not feeling tired, and it also has a mild addictive effect. Why this is bad is obvious: you feel tired when your body needs rest. Not getting that rest can cause tiny amounts of damage (stress) to various systems that compounds to serious problems over the long term. And caffeine makes that worse because you're not just avoiding rest, but instead tricked into being more active.

The one case where I personally feel that coffee is fine is first thing in the morning. I know some people will argue that caffeine first thing in the morning disrupts your brain's natural waking-up process, but I live in the modern world with alarm clocks and schedules. I can't just wake up when my brain wants to wake up and wait for it to casually boot up every morning. Caffeine is a simple way to jumpstart the day, in my opinion.